[gaius]

The higher up you are, the longer you're expected to stay

This is partly it, but also, it's because as you get more senior, your personal network within the company counts for more and more. If you're going to make big, potentially controversial decisions, then you can't afford to argue every point - you'll get nowhere. You need a critical mass of people who already trust and respect you, and who you trust and respect in return, so you don't have to get bogged down in managing day-to-day stuff. That takes years to develop.

I have seen this a few times, people who job hop for promotions then end up in a position where they're so high up they're starved of oxygen - none of their direct reports take them seriously, ringleaders in the middle ranks openly disrespect them, in a few months they're gone. That's damaging to the organization too, partly because it paralyzes it, and partly because it destroys morale (and confidence in the top leadership).